Endotracheal tube apparatus

ABSTRACT

An apparatus for monitoring EMG signals of a patient&#39;s laryngeal muscles includes an endotracheal tube having an exterior surface and a first location configured to be positioned at the patient&#39;s vocal folds. A first electrode is formed on the exterior surface of the endotracheal tube substantially below the first location. A second electrode is formed on the exterior surface of the endotracheal tube substantially above the first location. The first and second electrodes are configured to receive the EMG signals from the laryngeal muscles when the endotracheal tube is placed in a trachea of the patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e)(1) to U.S.Provisional Patent Application Ser. No. 61/248,294, filed Oct. 2, 2009,entitled “Endotracheal Tube Apparatus”; and the entire teachings ofwhich are incorporated herein by reference.

BACKGROUND

Endotracheal tubes include electrodes that are designed to make contactwith a patient's vocal cords to facilitate electromyographic (EMG)monitoring of the vocal cords during surgery when connected to an EMGmonitoring device. Endotracheal tubes provide an open airway for patientventilation, and provide for monitoring of EMG activity of the intrinsiclaryngeal musculature when connected to an appropriate EMG monitor.Endotracheal tubes can provide continuous monitoring of the nervessupplying the laryngeal musculature during surgical procedures.

SUMMARY

One embodiment is directed to an apparatus for monitoring EMG signals ofa patient's laryngeal muscles. The apparatus includes an endotrachealtube having an exterior surface and a first location configured to bepositioned at the patient's vocal folds. A first electrode is formed onthe exterior surface of the endotracheal tube substantially below thefirst location. A second electrode is formed on the exterior surface ofthe endotracheal tube substantially above the first location. The firstand second electrodes are configured to receive the EMG signals from thelaryngeal muscles when the endotracheal tube is placed in a trachea ofthe patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an EMG endotracheal tube made from extruded polymeraccording to one embodiment.

FIG. 2 shows a close-up view of a portion of the endotracheal tube shownin FIG. 1 according to one embodiment.

FIG. 3 shows an EMG endotracheal tube made from PVC according to oneembodiment.

FIG. 4 shows a close-up view of a portion of the endotracheal tube shownin FIG. 3 according to one embodiment.

FIG. 5 shows an EMG endotracheal tube with conductive ink electrodesprinted on the tube according to one embodiment.

FIG. 6 shows a close-up view of a portion of the endotracheal tube shownin FIG. 5 according to one embodiment.

FIG. 7 is a diagram illustrating a cross-sectional view of theendotracheal tube shown in FIG. 5 according to one embodiment.

FIG. 8 shows an EMG endotracheal tube with multiple pairs of conductiveink electrodes printed around the circumference of the tube according toone embodiment.

FIG. 9 shows a close-up view of a portion of the endotracheal tube shownin FIG. 8 according to one embodiment.

FIG. 10 is a diagram illustrating a cross-sectional view of theendotracheal tube shown in FIG. 8 according to one embodiment.

FIG. 11 shows an EMG endotracheal tube with a primary cuff and asecondary cuff according to one embodiment.

FIG. 12A shows the secondary cuff of the endotracheal tube shown in FIG.11 with conductive ink electrodes printed on the secondary cuffaccording to one embodiment.

FIG. 12B shows the secondary cuff of the endotracheal tube shown in FIG.11 according to another embodiment.

FIG. 13 shows an EMG endotracheal tube with a visual indicator fortracking and verifying electrode location according to one embodiment.

FIG. 14 shows a close-up view of a portion of the endotracheal tubeshown in FIG. 13 according to one embodiment.

FIG. 15 shows an EMG endotracheal tube with a magnet indicator fortracking and verifying electrode location according to one embodiment.

FIGS. 16 and 17 show close-up views of a portion of the endotrachealtube shown in FIG. 15 according to one embodiment.

FIG. 18 shows an EMG endotracheal tube with a coupling adapter toprovide rotational freedom according to one embodiment.

FIG. 19 shows a close-up view of a portion of the endotracheal tubeshown in FIG. 18 according to one embodiment.

FIG. 20 shows an EMG endotracheal tube with ribs on the top and bottomof the EMG electrodes according to one embodiment.

FIG. 21 shows a close-up view of a portion of the endotracheal tubeshown in FIG. 20 according to one embodiment.

FIG. 22 shows an EMG endotracheal tube with conductive tape on thesurface of the tube for recording EMG signals according to oneembodiment.

FIG. 23 shows a close-up view of a portion of the endotracheal tubeshown in FIG. 22 according to one embodiment.

FIG. 24 shows an EMG endotracheal tube with a custom extruded PVC tubeaccording to one embodiment.

FIGS. 25 and 26 show close-up views of a portion of the endotrachealtube shown in FIG. 24 according to one embodiment.

FIG. 27 shows an EMG endotracheal tube positioned within a patient'sthroat according to one embodiment.

FIGS. 28A-28D show an EMG endotracheal tube with electrodes having anincreased surface area according to various embodiments.

FIG. 29 shows an EMG endotracheal tube with an overall shape that iscurved to match the shape of a human throat according to one embodiment.

FIG. 30 shows a cross-sectional view of an EMG endotracheal tube withelectrodes configured to reduce or eliminate rotational sensitivityaccording to one embodiment.

FIG. 31 shows an EMG endotracheal tube with electrodes configured toreduce or eliminate rotational sensitivity according to anotherembodiment.

FIG. 32 shows a cuff for an EMG endotracheal tube according to oneembodiment.

FIG. 33 shows an electrical schematic diagram of an electrode arrayconfigured to be used in an EMG endotracheal tube according to oneembodiment.

FIG. 34 shows flexible, expanding electrodes configured to be used in anEMG endotracheal tube according to one embodiment.

FIG. 35A shows a first side view (posterior side) of an EMG endotrachealtube with three electrodes according to one embodiment.

FIG. 35B shows a second side view (rotated 90 degrees from the viewshown in FIG. 35A) of the EMG endotracheal tube shown in FIG. 35Aaccording to one embodiment.

FIG. 35C is a diagram illustrating a cross-sectional view of theendotracheal tube shown in FIGS. 35A and 35B according to oneembodiment.

FIG. 36A shows a first side view (posterior side) of an EMG endotrachealtube with four electrodes according to one embodiment.

FIG. 36B shows a second side view (rotated 90 degrees from the viewshown in FIG. 36A) of the EMG endotracheal tube shown in FIG. 36Aaccording to one embodiment.

FIG. 36C is a diagram illustrating a cross-sectional view of theendotracheal tube shown in FIGS. 36A and 36B according to oneembodiment.

FIG. 37A shows a first side view (posterior side) of an EMG endotrachealtube with four electrodes according to another embodiment.

FIG. 37B shows a second side view (rotated 90 degrees from the viewshown in FIG. 37A) of the EMG endotracheal tube shown in FIG. 37Aaccording to one embodiment.

FIG. 38 shows a side view of an EMG endotracheal tube with a pluralityof ring electrodes according to one embodiment.

FIGS. 39A-39E show EMG endotracheal tubes with tube placement markingsaccording to various embodiments.

DETAILED DESCRIPTION

FIG. 1 shows an EMG endotracheal tube 100 made from extruded polymer.FIG. 2 shows a close-up view of a portion of the endotracheal tube 100shown in FIG. 1. Endotracheal tube 100 includes solid wires 102, fitting104, cuff inflating conduit 106, extruded polymer tube 110, wireelectrodes 112, and primary cuff 114. Solid wires 102 are connected towire electrodes 112 at interconnection 108. Tube 110 transports gases toand from the lungs. Fitting 104 is configured to be connected to arespirating machine (not shown) for injecting air into the lungs andwithdrawing air from the lungs. Cuff inflating conduit 106 is configuredto be connected to a source of compressed air (not shown) for inflatingcuff 114. Cuff inflating conduit 106 communicates with a lumen locatedin the wall of tube 110, and the lumen communicates with primary cuff114. After endotracheal tube 100 is inserted into the trachea of apatient, electrode wires 112 sense EMG signals, which are output to anEMG processing machine, such as nerve integrity monitor (NIM) device120, via solid wires 102. Die cut tape may be used to tape tube 110 to apatient's mouth to secure the tube and keep it appropriately positioned.

In one embodiment, the NIM 120 is configured to determine when theelectrodes 112 are in contact with the vocal folds, and is configured toprovide an alert to the surgeon when such contact is lost. In oneembodiment, the NIM 120 is also configured to determine whether theelectrodes 112 are in contact with muscle or tissue based on thereceived signals. In one embodiment, EMG tube 100 is configured towirelessly communicate with the NIM 120, and the NIM 120 is configuredto wirelessly monitor the electrodes 112. In form of this embodiment,the NIM 120 wirelessly transmits energy to the electrodes 112, and theelectrodes 112 wirelessly transmit EMG signals to the NIM 120.

Some existing endotracheal tubes can rotate, which causes the electrodesto move away from the vocal folds. In contrast, tube 110 includes aflexible tube segment 113 that is configured to make contact with thevocal folds, and exposed electrodes 112 are formed over the flexibletube segment 113. The flexible tube segment 113 is more flexible orsofter (e.g., made from a low durometer material) than the remainder ofthe tube 110, which allows the electrodes 112 to maintain betteropposition with the vocal folds and reduce or eliminate translationaland rotational movement of the tube 110. In one embodiment, primary cuff114 is formed from a tacky, low-durometer material to contour againstthe tracheal rings, which helps to reduce or eliminate translational androtational movement of the tube 110. In one embodiment, electrodes 112are about 1.3 inches long. In another embodiment, electrodes 112 areabout 1.9 inches long. Extending the length of electrodes 112 helps thetube 110 to become less sensitive to neck extension.

In one embodiment, tube 110 is a braided tube that is more flexible thanconventional solid polymer tubes, and that reduces kinking. Tube 110according to one embodiment is formed from a braided polymer or nitinolwithin a thin-walled tube, and reduces or eliminates rotation of thetube at the vocal folds, while allowing a proximal portion of the tubeto rotate.

FIG. 3 shows an EMG endotracheal tube 300 made from PVC. FIG. 4 shows aclose-up view of a portion of the endotracheal tube 300 shown in FIG. 3.Endotracheal tube 300 includes solid wires 302, fitting 304, cuffinflating conduit 306, PVC tube 310, taped-on electrodes 312, primarycuff 314, and electrode wires 316. Solid wires 302 are connected toelectrode wires 316 at interconnection 308, and electrode wires 316 areconnected to taped-on electrodes 312. Tube 310 transports gases to andfrom the lungs. Fitting 304 is configured to be connected to arespirating machine (not shown) for injecting air into the lungs andwithdrawing air from the lungs. Cuff inflating conduit 306 is configuredto be connected to a source of compressed air (not shown) for inflatingcuff 314. Cuff inflating conduit 306 communicates with a lumen locatedin the wall of tube 310, and the lumen communicates with primary cuff314. After endotracheal tube 300 is inserted into the trachea of apatient, taped-on electrodes 312 sense EMG signals, which are output toan EMG processing machine (e.g., NIM device 120) via solid wires 302.

FIG. 5 shows an EMG endotracheal tube 500 with conductive ink electrodesprinted on the tube according to one embodiment. FIG. 6 shows a close-upview of a portion of the endotracheal tube 500 shown in FIG. 5 accordingto one embodiment. Endotracheal tube 500 includes solid wires 502,fitting 504, cuff inflating conduit 506, PVC tube 510, conductive inkelectrodes 512, and primary cuff 514. Solid wires 502 are connected toconductive ink electrodes 512 at interconnection 508. Tube 510transports gases to and from the lungs. Fitting 504 is configured to beconnected to a respirating machine (not shown) for injecting air intothe lungs and withdrawing air from the lungs. Cuff inflating conduit 506is configured to be connected to a source of compressed air (not shown)for inflating cuff 514. Cuff inflating conduit 506 communicates with alumen 522 (FIG. 7) located in the wall 520 of tube 510, and the lumen522 communicates with primary cuff 514. After endotracheal tube 500 isinserted into the trachea of a patient, conductive ink electrodes 512sense EMG signals, which are output to an EMG processing machine (e.g.,NIM device 120) via solid wires 502.

FIG. 7 is a diagram illustrating a cross-sectional view of theendotracheal tube 500 shown in FIG. 5 according to one embodiment. Asshown in FIG. 7, lumen 522 is located in the wall 520 of tube 510 forinflating the cuff 514. Conductive ink electrodes 512 are formed on theouter surface of wall 520. In one embodiment, conductive ink electrodes512 are formed by tracing or printing a silver filled polymer conductiveink or a carbon conductive ink on tube 510. Conductive inks areavailable in variety of flowable material choices such as Silver,Carbon, Gold, Platinum, Palladium, Silver-Tungsten, and Silver-Titanium.Conductive inks can be deposited on the substrate using various knowntechnologies such as PAD printing, Screen printing, Ink jet dispensing,digital printing, Micropen dispensing, painting, vapor deposition, andplasma sputtering. Conductive inks can be used both for stimulation andrecording purposes in nerve monitoring applications.

FIG. 8 shows an EMG endotracheal tube 800 with multiple pairs ofconductive ink electrodes printed around the circumference of the tubeaccording to one embodiment. FIG. 9 shows a close-up view of a portionof the endotracheal tube 800 shown in FIG. 8 according to oneembodiment. Endotracheal tube 800 includes fitting 804, cuff inflatingconduit 806, PVC tube 810, conductive ink electrodes 812, and primarycuff 814. Tube 810 transports gases to and from the lungs. Fitting 804is configured to be connected to a respirating machine (not shown) forinjecting air into the lungs and withdrawing air from the lungs. Cuffinflating conduit 806 is configured to be connected to a source ofcompressed air (not shown) for inflating cuff 814. Cuff inflatingconduit 806 communicates with a lumen 822 (FIG. 10) located in the wall820 of tube 810, and the lumen 822 communicates with primary cuff 814.After endotracheal tube 800 is inserted into the trachea of a patient,conductive ink electrodes 812 sense EMG signals, which are output to anEMG processing machine (e.g., NIM device 120) via solid wires connectedto the electrodes 812 (e.g., solid wires 502 shown in FIG. 5).

FIG. 10 is a diagram illustrating a cross-sectional view of theendotracheal tube 800 shown in FIG. 8 according to one embodiment. Asshown in FIG. 10, lumen 822 is located in the wall 820 of tube 810 forinflating the cuff 814. Multiple pairs of conductive ink electrodes 812are formed around the circumference of the tube 810 to achieveuninterrupted EMG recording even when the tube 810 is shiftedrotationally. In one embodiment, conductive ink electrodes 812 areformed by tracing or printing a silver filled polymer conductive ink ontube 810.

FIG. 11 shows an EMG endotracheal tube 1100 with a primary cuff 1114 anda secondary cuff 1130 according to one embodiment. FIG. 12A shows aclose-up view of the secondary cuff 1130 of the endotracheal tube shownin FIG. 11 with conductive ink electrodes 1132 printed on the secondarycuff 1130 according to one embodiment. FIG. 12B shows a close-up view ofthe secondary cuff 1130 of the endotracheal tube shown in FIG. 11according to another embodiment. The embodiment of the secondary cuff1130 shown in FIG. 12A is identified by reference number 1130-1, and theembodiment shown in FIG. 12B is identified by reference number 1130-2.Endotracheal tube 1100 includes PVC tube 1110, primary cuff 1114, andsecondary cuff 1130 with conductive ink electrodes 1132 formed thereon.Tube 1110 transports gases to and from the lungs. At least one cuffinflating conduit (not shown) is configured to be connected to a sourceof compressed air (not shown) for inflating cuffs 1114 and 1130. Afterendotracheal tube 1100 is inserted into the trachea of a patient, thesecondary cuff 1130 is inflated and the conductive ink electrodes 1132come in contact with the vocal folds and sense EMG signals from thevocal folds. The sensed signals are output to an EMG processing machine(e.g., NIM device 120) via wires connected to the electrodes 1132. Inone embodiment, the secondary cuff 1130 is made of a compliant orsemi-compliant material, and conductive ink electrodes 1132 are formedby tracing or printing a silver filled polymer conductive ink onsecondary cuff 1130. The secondary cuff 1130 with the silver ink printedthereon helps establish a better electrode contact when inflated overthe vocal folds. Electrodes 1132 may be sprayed on secondary cuff 1130or tube 1110, and may cover substantially the entire surface ofsecondary cuff 1130. Electrodes 1132 may take a variety of shapes orforms other than that shown in FIG. 12A, such as any of the shapes orforms shown in any of the other Figures of the present disclosure, orother shapes. In other embodiments, EMG tube 1100 may include three ormore cuffs.

Secondary cuff 1130 may also have a different shape than that shown inFIG. 12A, such as that shown in FIG. 12B. As shown in FIG. 12B,secondary cuff 1130-2 has a flattened peanut shape with two rounded ends1133 and 1137 that taper to a mid portion 1135. The flattened peanutshape of the cuff 1130-2 according to one embodiment fits or contours tothe shape of the vocal folds, and helps to reduce or eliminatetranslational and rotational movement of the tube 1110. In anotherembodiment, the secondary cuff 1130 is formed from an elastomer or foampillow with two rounded ends that taper to a mid portion like that shownin FIG. 12B. In one form of this embodiment, the ends of the pillow havea substantially triangular cross-section. In one embodiment, thesecondary cuff 1130 includes one or more position sensors to monitor theposition or location of the tube 1110.

FIG. 13 shows an EMG endotracheal tube 1300 with a visual indicator 1320for tracking and verifying electrode location according to oneembodiment. FIG. 14 shows a close-up view of a portion of theendotracheal tube 1300 shown in FIG. 13 according to one embodiment.Endotracheal tube 1300 includes solid wires 1302, fitting 1304, cuffinflating conduit 1306, PVC tube 1310, electrodes 1312, primary cuff1314, and visual indicator 1320. Solid wires 1302 are connected toelectrodes 1312. Tube 1310 transports gases to and from the lungs.Fitting 1304 is configured to be connected to a respirating machine (notshown) for injecting air into the lungs and withdrawing air from thelungs. Cuff inflating conduit 1306 is configured to be connected to asource of compressed air (not shown) for inflating cuff 1314. Cuffinflating conduit 1306 communicates with a lumen located in the wall oftube 1310, and the lumen communicates with primary cuff 1314. Afterendotracheal tube 1300 is inserted into the trachea of a patient,electrodes 1312 sense EMG signals, which are output to an EMG processingmachine (e.g., NIM device 120) via solid wires 1302.

In one embodiment, visual indicator 1320 is a bright lit light emittingdiode (LED) or fiber optic light source that is used to track and verifythe location of the electrodes 1312. The visual indicator 1320 is placedon the surface of the tube 1310 near the electrodes 1312 to identify theelectrode position with respect to the vocal fold after tube intubation.A user can see the light spot facing anterior and mark the spot on thepatient's skin. In another embodiment, visual indicator 1320 is an LEDband that surrounds a portion or the entire circumference of tube 1310.

FIG. 15 shows an EMG endotracheal tube 1500 with a magnet indicator 1520for tracking and verifying electrode location according to oneembodiment. FIGS. 16 and 17 show close-up views of a portion of theendotracheal tube 1500 shown in FIG. 15 according to one embodiment.Endotracheal tube 1500 includes solid wires 1502, cuff inflating conduit1506, tube 1510, electrodes 1512, primary cuff 1514, and magneticindicator 1520. Solid wires 1502 are connected to electrodes 1512. Tube1510 transports gases to and from the lungs. A fitting of the tube 1500is configured to be connected to a respirating machine (not shown) forinjecting air into the lungs and withdrawing air from the lungs. Cuffinflating conduit 1506 is configured to be connected to a source ofcompressed air (not shown) for inflating cuff 1514. Cuff inflatingconduit 1506 communicates with a lumen located in the wall of tube 1510,and the lumen communicates with primary cuff 1514. After endotrachealtube 1500 is inserted into the trachea of a patient, electrodes 1512sense EMG signals, which are output to an EMG processing machine (e.g.,NIM device 120) via solid wires 1502.

In one embodiment, magnetic indicator 1520 is a tiny magnet that is usedto track and verify the location of the electrodes 1512. The magneticindicator 1520 is placed on the surface of the tube 1510 near theelectrodes 1512 to identify the electrode position with respect to thevocal fold after tube intubation. A user can track and locate the magnetinside the patient with a device 1530 (FIG. 17) that includes a magnetpick-up sensor.

In addition to the LED-based and magnet-based techniques described abovewith respect to FIGS. 13-17, other embodiments may use other techniquesfor determining electrode location within a patient, such as thefollowing: (1) locating an anatomy landmark; (2) Automatic PeriodicStimulation (APS) electrode tracking; (3) sonar/ultra sound (similar toa wall stud finder); (4) surgical navigation using a coil; (5) use ofstimulator combined with locating device, and synchronizing the lightingof LED with the stimulator pulse of the wand; (6) use of anaccelerometer (e.g., positioned on the cuff) to monitor movement; (7)use of a vibration sensor and air inlets and outlets so that air flowpast the vocal folds causes vibration that is sensed by the vibrationsensor; (8) use of an ultrasonic transducer in or on the tube, and asensing circuit external to the body; (9) use of a resonant circuit forpositional and rotational sensing (could use stimulator channel toprovide pulses); use resonant vibration near vocal fold tissueresonance; mechanical impedance of the vocal fold is detected byimpedance match and energy transfer to surrounding tissue; use surfaceacoustic wave or other mechanical resonator; (10) use of a pressuresensor or pressure sensor array near the electrode sites to detectengagement with the vocal folds (e.g., a pressure sensitive surface withcapacitive sensor on each side of the tube); (11) wireless sensorslinked to a wireless interface (e.g., the tube may include a wirelessvideo chip to send signals to an external monitor (e.g.,picture-in-picture on the NIM or miniscreen) to view placement in realtime); (12) temperature sensors (temperature will be higher when incontact with the vocal folds); (13) embedded fiber optic viewer withlight source at proximal end and viewing window near electrodes(software in NIM to identify position); (14) one or more RF ID tagsincorporated in or on the tube with signals sent to an external deviceor the NIM for reading and evaluation; (15) flexible piezo strips formonitoring the movement of one or more portions of the tube, such as theflexible tube segment 113 (FIGS. 1 and 2)—monitoring movement of theflexible tube segment 113 indirectly results in monitoring of themovement of the vocal folds; (16) impedance monitors placed around oneor more portions of the tube, such as around tube segment 113 (FIGS. 1and 2), to detect changes in the diameter of the tube at the vocal folds(such impedance monitoring allows the vocal fold movement to bemonitored without recording EMG potentials); and (17) use electrodeswith the ability to differentiate between muscle contact and non-musclecontact, which helps the NIM to ensure proper position and contact.

FIG. 18 shows an EMG endotracheal tube 1800 with a coupling adapter 1820to provide rotational freedom according to one embodiment. FIG. 19 showsa close-up view of a portion of the endotracheal tube 1800 shown in FIG.18 according to one embodiment. Endotracheal tube 1800 includes solidwires 1802, fitting 1804, cuff inflating conduit 1806, PVC tube 1810,electrodes 1812, primary cuff 1814, and plastic coupling adapter 1820.Solid wires 1802 are connected to electrodes 1812. Tube 1810 transportsgases to and from the lungs. Fitting 1804 is configured to be connectedto a respirating machine (not shown) for injecting air into the lungsand withdrawing air from the lungs. Cuff inflating conduit 1806 isconfigured to be connected to a source of compressed air (not shown) forinflating cuff 1814. Cuff inflating conduit 1806 communicates with alumen located in the wall of tube 1810, and the lumen communicates withprimary cuff 1814. After endotracheal tube 1800 is inserted into thetrachea of a patient, electrodes 1812 sense EMG signals, which areoutput to an EMG processing machine (e.g., NIM device 120) via solidwires 1802.

In one embodiment, after insertion of the endotracheal tube 1800 into apatient, the tube is taped to the patient's mouth. The coupling adapter1820 is positioned at the proximal end (away from the patient's mouth),and allows the proximal end of the tube 1810 to swivel around asindicated by arrow 1830 in FIG. 19, which minimizes rotational movementof the distal portion of the tube 1810 in the patient. In oneembodiment, the coupling adapter 1820 allows thirty degrees of rotationin either direction. In another embodiment, endotracheal tube 1800includes a tube within a tube configuration that allows a proximalportion of the tube to rotate while preventing rotation of the distalportion of the tube. In one embodiment, primary cuff 1814 is formed froma sticky or tacky material (e.g., a tacky balloon) to help prevent thedistal portion of the tube from rotating.

FIG. 20 shows an EMG endotracheal tube 2000 with ribs 2020 on the topand bottom of the EMG electrodes 2012 according to one embodiment. FIG.21 shows a close-up view of a portion of the endotracheal tube 2000shown in FIG. 20 according to one embodiment. Endotracheal tube 2000includes solid wires 2002, fitting 2004, cuff inflating conduit 2006,tube 2010, electrodes 2012, primary cuff 2014, and ribs 2020. Solidwires 2002 are connected to electrodes 2012. Tube 2010 transports gasesto and from the lungs. Fitting 2004 is configured to be connected to arespirating machine (not shown) for injecting air into the lungs andwithdrawing air from the lungs. Cuff inflating conduit 2006 isconfigured to be connected to a source of compressed air (not shown) forinflating cuff 2014. Cuff inflating conduit 2006 communicates with alumen located in the wall of tube 2010, and the lumen communicates withprimary cuff 2014. After endotracheal tube 2000 is inserted into thetrachea of a patient, electrodes 2012 sense EMG signals, which areoutput to an EMG processing machine (e.g., NIM device 120) via solidwires 2002.

The ribs 2020 according to one embodiment provide a positive feel whenpassing the vocal fold during intubation, and the ribs 2020 on top andbottom of the vocal fold will not allow the tube 2010 to move out ofposition. In one embodiment, the ribs 2020 are shaped to match thecontour of the opening, and are made with compliant or semi-compliantmaterial. In another embodiment, ribs 2020 are implemented withinflatable balloons.

FIG. 22 shows an EMG endotracheal tube 2200 with conductive tape on thesurface of the tube for recording EMG signals according to oneembodiment. FIG. 23 shows a close-up view of a portion of theendotracheal tube 2200 shown in FIG. 22 according to one embodiment.Endotracheal tube 2200 includes fitting 2204, cuff inflating conduit2206, tube 2210, electrodes 2212, and primary cuff 2214. Solid wires areconnected to electrodes 2212. Tube 2210 transports gases to and from thelungs. Fitting 2204 is configured to be connected to a respiratingmachine (not shown) for injecting air into the lungs and withdrawing airfrom the lungs. Cuff inflating conduit 2206 is configured to beconnected to a source of compressed air (not shown) for inflating cuff2214. Cuff inflating conduit 2206 communicates with a lumen located inthe wall of tube 2210, and the lumen communicates with primary cuff2214. After endotracheal tube 2200 is inserted into the trachea of apatient, electrodes 2212 sense EMG signals, which are output to an EMGprocessing machine (e.g., NIM device 120) via solid wires attached tothe electrodes 2212.

In the embodiment illustrated in FIGS. 22 and 23, electrodes 2212 arestrips of conducting tape that stick to the surface of the tube 2210. Inone embodiment, the conducting tape is a woven material, and replacesthe solid wire electrodes found in some conventional tubes (2 channel ormultiple pairs). In one embodiment, one or more of the strips 2212 shownin FIGS. 22 and 23 comprise a piezo strip for monitoring movement of thetube 2210. In another embodiment, electrodes 2212 are covered with anexpandable, conductive foam that expands when it absorbs moisture,thereby providing improved contact with the vocal folds.

FIG. 24 shows an EMG endotracheal tube 2400 with a custom extruded PVCtube according to one embodiment. FIGS. 25 and 26 show close-up views ofa portion of the endotracheal tube 2400 shown in FIG. 24 according toone embodiment. Endotracheal tube 2400 includes solid wires 2402,fitting 2404, cuff inflating conduit 2406, tube 2410, electrodes 2412,and primary cuff 2414. Solid wires 2402 are connected to electrodes2412. Tube 2410 transports gases to and from the lungs. Fitting 2404 isconfigured to be connected to a respirating machine (not shown) forinjecting air into the lungs and withdrawing air from the lungs. Cuffinflating conduit 2406 is configured to be connected to a source ofcompressed air (not shown) for inflating cuff 2414. Cuff inflatingconduit 2406 communicates with a lumen located in the wall of tube 2410,and the lumen communicates with primary cuff 2414. After endotrachealtube 2400 is inserted into the trachea of a patient, electrodes 2412sense EMG signals, which are output to an EMG processing machine (e.g.,NIM device 120) via solid wires 2402.

In one embodiment, tube 2410 comprises a custom extruded PVC tube (rigidor reinforced), and the PVC cuff is not sticky like a silicone cuff. Thesize of the custom extruded PVC tube 2410 according to one embodiment isclose to standard off-the-shelf endotracheal tubes.

Features of embodiments of the EMG endotracheal tubes described hereininclude: (1) more placement tolerant than conventional tubes; (2) NIM isused to help place the tube; (3) the electrode is periodically checkedto assure constant contact; (4) intentional bend in correct directionfor proper tube insertion; (5) include high brightness LED in tube toobserve placement through the skin; (6) use external Hall sensors withmagnets in the tube to sense correct tube placement; (7) kit-pack tapesfor stabilizing the tube; (8) improved means to detect EMG generatorsand shunt tissue; (9) use muscle “artifact” as an indicator of properplacement (artifact can be minimized by adjusting tube position); (10)fiber optic bundle connected to light source or camera; (11) a “fixture”molded at the proximal end of the tube to register on the patientanatomy for proper orientation; (12) improved way and connector forplugging into the patient box; (13) creation of 4-channels from2-channels via added connectors (not added wires) or cross-point switchwithin the NIM; (14) providing a signal from the NIM to measureresistance and phase angle of tissue contacting the electrodes to decideif there is enough EMG generator tissue vs. shunt tissue; (15) EMG tubewith reduced overall outer diameter; and (16) reduced cost and qualityassociated issues with custom extruded silicone tubing by utilizingstandard off the shelf endotracheal tube. Additional features andinformation are set forth below.

The EMG tube electrodes according to one embodiment may contact both EMGgenerators (striated muscle) and shunt tissue (conductive tissue thatdoes not generate EMG signals but which does conduct current, thusshunting (reducing) the EMG signal available for the amplifier). A “highquality tube placement” has a high ratio of EMG generator tissue toshunt tissue.

Embodiments of the EMG endotracheal tubes described herein may include aconducting hydro gel coating on the electrodes, such as electrodes 112(FIG. 1). Coating the electrodes with a conducting hydro gel increasesthe contact surface of the electrodes, allows for more rotation of theEMG tube without a loss of contact with the vocal folds, and results inan improved recorded signal. Some embodiments may use paddle electrodesfor posterior and anterior monitoring, including monitoring arytenoidsand posterior cricoarytenoid (PCA).

There are some problems with existing EMG endotracheal, such as: (1)ridges on the outside of the tube can cause tissue irritation; (2) thetube can shift rotationally during surgery; and (3) the tube wall is toothick. These problems are addressed in one embodiment in the followingways: (1) use of a non-silicone material such as pebax with Teflon forthe tube, which allows the tube to slide easily (a high frictionmaterial may be used for the cuff to help prevent translational shift);(2) placing bumps for wires on the inner diameter (ID) of the tube; (3)splicing together different pieces of tubing along the length (each withpotentially a different cross-sectional shape) to get a more optimalcross-sectional geometry that more closely matches a patient's anatomy,such as using a first tube portion near the proximal end with a circularcross-section to allow rotation and a second tube portion near the vocalfolds with a triangular cross-section (e.g., with a circular ortriangular inner diameter); (4) just above the electrodes, adding aregion of lower wall thickness to de-couple upper sections from lowersection; and (5) decoupling the proximal end of the tube from the distalend by switching to a braided tube from a spring coil reinforced tube.

FIG. 27 shows an EMG endotracheal tube 2700 positioned within apatient's throat according to one embodiment. Endotracheal tube 2700includes fitting 2704, tube 2710, electrodes 2712, primary cuff 2714,esophageal extension 2720, and esophageal electrodes 2722. The portionsof the patient's anatomy shown in FIG. 27 include tongue 2730, trachea2732, and esophagus 2734. Tube 2710 transports gases to and from thelungs. Fitting 2704 is configured to be connected to a respiratingmachine (not shown) for injecting air into the lungs and withdrawing airfrom the lungs. A cuff inflating conduit is configured to be connectedto a source of compressed air for inflating cuff 2714. Afterendotracheal tube 2700 is inserted into the trachea 2732 of the patient,electrodes 2712 sense EMG signals, which are output to an EMG processingmachine (e.g., NIM device 120) via solid wires connected to electrodes2712.

As shown in FIG. 27, esophageal extension 2720 extends away from thetube 2710 and into the patient's esophagus 2734. The esophagealelectrodes 2722 formed on the extension 2720 sense signals from thebackside muscles of the vocal folds from the esophagus 2734. Theelectrodes 2722 according to one embodiment are used to record EMGsignals of laryngeal muscles behind the larynx. In one embodiment, theelectrodes 2722 are positioned behind the cricoid cartilage duringsurgery. Most of the muscles innervated by the recurrent laryngeal nerve(RLN) are behind and posterolateral to the larynx (e.g., arytenoids,posterior cricoarytenoid (PCA), and lateral cricoarytenoid (LCA)).Positioning the electrodes 2722 behind the cricoid cartilage providessuperior EMG signals. In one embodiment, esophageal extension 2720 isalso used to set both the depth of insertion of the tube 2710 and theangular placement.

FIG. 28A shows an EMG endotracheal tube 2800A with electrodes having anincreased surface area according to one embodiment. Tube 2800A includeselectrode 2802A, which has a sinusoidal wave shape that extends aroundthe circumference of the tube 2800A with peaks and valleys that extendin a longitudinal direction of the tube 2800A.

FIG. 28B shows an EMG endotracheal tube 2800B with electrodes having anincreased surface area according to another embodiment. Tube 2800Bincludes electrodes 2802B, which are formed around a circumference ofthe tube 2800B and extend in a longitudinal direction of the tube 2800B.Electrodes 2802B include a first set of electrodes 2802B-1 that areinterleaved with and longitudinally displaced from a second set ofelectrodes 2802B-2. The electrodes 2802B-1 are positioned closer to aproximal end of the tube 2800B than electrodes 2802B-2, and theelectrodes 2802B-2 are positioned closer to a distal end of the tube2800B than electrodes 2802B-1.

FIG. 28C shows an EMG endotracheal tube 2800C with electrodes having anincreased surface area according to another embodiment. Tube 2800Cincludes electrodes 2802C-1 and 2802C-2, which each have a sinusoidalwave shape that extends along a portion of the length of the tube 2800C,with peaks and valleys that extend in a lateral direction of the tube2800C.

FIG. 28D shows an EMG endotracheal tube 2800D with electrodes having anincreased surface area according to another embodiment. Tube 2800Dincludes electrode array 2802D, which includes a plurality of horizontalelectrodes 2802D-1 and 2802D-2 and a plurality of vertical electrodes2802D-3 and 2802D-4 that form a grid pattern. Horizontal electrodes2802D-1 and 2802D-2 extend laterally around a circumference of the tube2800D, and vertical electrodes 2802D-3 and 2802D-4 extend longitudinallyalong a portion of the length of the tube 2800D.

The electrode configurations shown in FIGS. 28A-28D help to reduce oreliminate rotational sensitivity of the tube. In one embodiment, theshape of the electrodes conforms to the vocal folds to avoid shuntingproblems.

FIG. 29 shows an EMG endotracheal tube 2900 with an overall shape thatis curved to match the shape of a human throat according to oneembodiment. Endotracheal tube 2900 includes fitting 2904, tube 2910,electrodes 2912, and primary cuff 2914. Tube 2910 transports gases toand from the lungs. Fitting 2904 is configured to be connected to arespirating machine (not shown) for injecting air into the lungs andwithdrawing air from the lungs. A cuff inflating conduit is configuredto be connected to a source of compressed air for inflating cuff 2914.After endotracheal tube 2900 is inserted into the trachea of thepatient, electrodes 2912 sense EMG signals, which are output to an EMGprocessing machine (e.g., NIM device 120) via solid wires connected toelectrodes 2912.

As shown in FIG. 29, tube 2910 is not a straight tube, but rather isbent or curved in at least one location along the length of the tube2910, such that the tube 2910 has a natural shape that matches orsubstantially matches the shape of a human throat. The curved shape ofthe tube 2910 provides tactual feel for proper placement in a patient.

FIG. 30 shows a cross-sectional view of an EMG endotracheal tube 3000with electrodes configured to reduce or eliminate rotational sensitivityaccording to one embodiment. Four electrodes 3002A-3002D are positionedon tube 3004 and extend longitudinally along a portion of the length ofthe tube 3004 (i.e., into and out of the paper in FIG. 30). In theillustrated embodiment, the four electrodes 3002A-3002D are spacedequally apart along the circumference of the tube 3004. Electrode 3002Acorresponds to channel 1+ and channel 3+. Electrode 3002B corresponds tochannel 2+ and channel 4−. Electrode 3002C corresponds to channel 1− andchannel 4+. Electrode 3002D corresponds to channel 2− and channel 3−.

As shown in FIG. 30, a four-electrode tube can be used to create fourchannels by using the diagonal pairs of electrodes for channels 3 and 4.This electrode configuration helps ensure that the tube will always havetwo good monitoring channels regardless of rotation, and thereby helpsreduce or eliminate rotational sensitivity of the tube. A four-electrodetube can also be used to create six channels (e.g., by using the top twoelectrodes for channel 5 and the bottom two electrodes for channel 6).In one embodiment, the NIM 120 (FIG. 1) is configured to display allfour or six channels. In another embodiment, the NIM 120 is configuredto determine which of the four or six channels are providing the bestsignal, and display only the best channel or channels. In oneembodiment, tube 3004 includes an identification component (e.g.,resistor, RF, magnet, digital) that causes the NIM 120 to switch into amulti-channel mode. The tube may also include one or more LEDs to verifythe depth of insertion of the tube. Rotational sensitivity may also bereduced or eliminated by multiplexing a large number of electrode pairs.

FIG. 31 shows an EMG endotracheal tube 3100 with electrodes configuredto reduce or eliminate rotational sensitivity according to anotherembodiment. EMG endotracheal tube 3100 includes tube 3110, primary cuff3114, and electrode carriers 3120A and 3120B. Each of the electrodecarriers 3120A and 3120B is donut-shaped, and surrounds thecircumference of the tube 3110. The electrode carriers 3120A and 3120Bare spaced apart from each other along the length of the tube 3110.Electrode 3112A is formed on electrode carrier 3120A, and electrode3112B is formed on electrode carrier 3120B. Each of the electrodes 3112Aand 3112B has a sinusoidal wave shape that extends around thecircumference of the respective carrier 3120A and 3120B, with peaks andvalleys that extend in a longitudinal direction of the tube 3110. In oneembodiment, electrode 3112A is a negative electrode and electrode 3112Bis a positive electrode. The electrode configuration shown in FIG. 31helps to reduce or eliminate rotational sensitivity of EMG endotrachealtube 3100.

In another embodiment, EMG endotracheal tube 3100 includes only a singledonut-shaped electrode carrier 3120A, and the carrier 3120A is slidablycoupled to the tube 3110 to allow the carrier 3120A to longitudinallyslide up and down along the length of the tube 3110. In one form of thisembodiment, a control member may be attached to the carrier 3120A toselectively cause the carrier 3120A to expand and allow sliding, or tocontract and prevent sliding. For example, the control member may causethe carrier 3120A to expand when the carrier 3120A is positioned at thevocal folds such that the carrier 3120A stays at that location while thetube 3110 is allowed to slide through the carrier 3120A. In oneembodiment, one or both of the carriers 3120A and 3120B may have acircular cross-sectional shape, or a non-circular cross-sectional shape(e.g., triangular shape).

FIG. 32 shows a cuff 3200 for an EMG endotracheal tube according to oneembodiment. Cuff 3200 includes an expandable cuff portion 3202 andtension members 3204. Cuff 3200 also includes a cylindrically-shapedopening 3206 that extends through the cuff 3200, and allows the cuff3200 to be slid onto an endotracheal tube. Tension members 3204 allowexpansion of the cuff portion 3202, but resist torsion and help tominimize rotation of cuff 3200 and the endotracheal tube. In oneembodiment, tension members 3204 are self-expanding and are formed froma shape memory material, such as nitinol. In one embodiment, tensionmembers 3204 are a nitinol framework or basket, and the cuff 3200includes electrodes formed thereon. In one form of this embodiment, thecuff 3200 is configured to atraumatically conform to the shape of thevocal folds.

FIG. 33 shows an electrical schematic diagram of an electrode arrayconfigured to be used in an EMG endotracheal tube according to oneembodiment. The electrode array includes five electrodes 3302 in a starconfiguration, with the electrodes 3302 sharing a common node 3304.Positive terminal 3306 is connected to the common node 3304. The arrayalso includes terminal 3308. In one embodiment, terminal 3306 andelectrodes 3302 are located on the tube, and terminal 3308 is located ona primary or secondary cuff of the tube. The electrode configurationshown in FIG. 33 helps to reduce or eliminate rotational sensitivity ofthe EMG endotracheal tube. Rotational sensitivity may also be reduced oreliminated by using two ring electrodes that surround the circumferenceof the tube at two locations (e.g., one ring electrode at the vocalfolds and a second ring electrode on a primary or secondary cuff of thetube).

FIG. 34 shows flexible, expanding electrodes configured to be used in anEMG endotracheal tube according to one embodiment. As shown in FIG. 34,a pair of spaced-apart retaining rings 3422 and 3424 each surround thecircumference of tube 3410. The rings 3422 and 3424 hold flexibleelectrodes 3412 in place between the rings. The electrodes 3412 extendlongitudinally along a portion of the length of tube 3410. The closerthat rings 3422 and 3424 are positioned toward each other along tube3410, the farther that the electrodes 3412 extend away from tube 3410.The farther that rings 3422 are positioned away from each other alongtube 3410, the closer that the electrodes 3412 are to the tube 3410. Theelectrodes 3412 may be used to mechanically stimulate the vocal chords.The vocal folds will push the flexible electrodes 3412 inward towardtube 3410.

In the event of movement of an EMG endotracheal tube during surgery, theEMG electrodes on the tube may lose contact with the target muscle andmay fail to provide the optimal EMG response. One embodiment provides anEMG endotracheal tube that is insensitive or substantially insensitiveto tube movement (rotational and vertical), and provides uninterruptedEMG recording even if the tube moves rotationally or vertically insidethe patient during surgery. One form of this embodiment is a tube withthree electrodes, with two electrodes configured to be positioned abovethe vocal folds and one electrode configured to be positioned below thevocal folds. Another form of this embodiment is a tube with fourelectrodes, with two electrodes configured to be positioned above thevocal folds and two electrodes configured to be positioned below thevocal folds, with the electrodes arranged equally angularly. Theelectrode configuration for these embodiments differs above and belowthe level of the vocal folds, which maximizes the signal differencebetween the activated muscle group and the inactive region. Theelectrodes above and below the level of the vocal folds improvemonitoring of electromyographic (EMG) signals from the muscles of thelarynx innervated by the recurrent laryngeal nerves (or thenon-recurrent laryngeal nerves) and external branch of the superiorlaryngeal nerves. The electrodes above and below the level of the vocalfolds provide posterior, lateral, and anterior monitoring of the larynx,for example; monitoring left and the right Vocalis muscle, Arytenoids,Thyroarytenoids, Posterior Cricoarytenoids, Lateral Cricoarytenoid, andCricothyroid muscles. Embodiments that are substantially insensitive totube position are described in further detail below with reference toFIGS. 35-37.

FIG. 35A shows a first side view (posterior side) of an EMG endotrachealtube 3500 with three electrodes according to one embodiment. FIG. 35Bshows a second side view (rotated 90 degrees from the view shown in FIG.35A) of the EMG endotracheal tube 3500 shown in FIG. 35A according toone embodiment. FIG. 35C is a diagram illustrating a cross-sectionalview of the endotracheal tube 3500 shown in FIGS. 35A and 35B accordingto one embodiment. As shown in FIGS. 35A-35C, endotracheal tube 3500includes tube 3510, electrodes 3512, and primary cuff 3514. Tube 3510transports gases to and from the lungs. A proximal end (left end in FIG.35A) of tube 3510 is configured to be connected to a respirating machine(not shown) for injecting air into the lungs and withdrawing air fromthe lungs. A cuff inflating conduit (not shown) is configured to beconnected to a source of compressed air (not shown) for inflating cuff3514. After endotracheal tube 3500 is inserted into the trachea of apatient, electrodes 3512 sense EMG signals, which are output to an EMGprocessing machine (e.g., NIM device 120).

Electrodes 3512 include three electrodes 3512A-3512C, which are formedaround a circumference of the tube 3510 and extend in a longitudinaldirection of the tube 3510. Electrode 3512B is positioned entirely onthe posterior side of the tube 3510 and is also referred to herein asposterior electrode 3512B. Electrodes 3512A and 3512C are positionedprimarily on the anterior side of the tube 3510 and are also referred toas anterior electrodes 3512A and 3512C. The anterior side of the tube3510 is the bottom half of the tube 3510 shown in FIG. 35C, and theposterior side of the tube 3510 is the top half of the tube 3510 shownin FIG. 35C. Each of the electrodes 3512A-3512C is coupled to arespective trace 3524A-3524C (trace 3524A is not visible in theFigures). Traces 3524A-3524C are positioned in a protected (masked)region 3528 of tube 3510. Posterior electrode 3512B is positioned in anexposed (unmasked) region 3526A of tube 3510. Anterior electrodes 3512Aand 3512C are positioned in an exposed (unmasked) region 3526B of tube3510.

In one embodiment, each of the electrodes 3512A-3512C has a length ofabout one inch, and extends laterally around a circumference of the tubefor a distance corresponding to an angle 3522 of about 90 degrees (i.e.,each of the electrodes 3512A-3512C has a width of about 25 percent ofthe total circumference of the tube). The electrodes 3512A-3512C arelaterally spaced apart around the circumference of the tube by adistance corresponding to an angle 3520 of about 30 degrees (i.e., thelateral spacing between each of the electrodes 3512A-3512C is about8.333 percent of the total circumference of the tube). In anotherembodiment, each of the electrodes 3512A-3512C extends laterally arounda circumference of the tube for a distance corresponding to an angle3522 of about 60 degrees, and the electrodes 3512A-3512C are laterallyspaced apart around the circumference of the tube by a distancecorresponding to an angle 3520 of about 60 degrees. In yet anotherembodiment, the electrodes 3512A-3512C are laterally spaced apart aroundthe circumference of the tube by a distance corresponding to an angle3520 of greater than about 15 degrees. In one embodiment, the distancearound the circumference of the tube from the center of one of theelectrodes 3512A-3512C to the center of an adjacent electrode is about110 degrees to 220 degrees. The posterior electrode 3512B is laterallypositioned between the two anterior electrodes 3512A and 3512C, and islongitudinally offset or displaced from the anterior electrodes 3512Aand 3512B. The posterior electrode 3512B is positioned closer to thedistal end (right side in FIGS. 35A and 35B) of the tube 3510 than theanterior electrodes 3512A and 3512C, and the anterior electrodes 3512Aand 3512C are positioned closer to the proximal end (left side in FIGS.35A and 35B) of the tube 3510 than the posterior electrode 3512B.

Tube 3510 includes an overlap region 3530 where a proximal portion ofthe posterior electrode 3512B longitudinally overlaps with a distalportion of the anterior electrodes 3512A and 3512C. The electrodes 3512do not physically overlap each other since they are laterally offsetfrom each other. In one embodiment, the overlap region 3530 is about 0.1inches long, and the overall length from a proximal end of the anteriorelectrodes 3512A and 3512C to a distal end of the posterior electrode3512B is about 1.9 inches. In another embodiment, the overlap region3530 is about 0.2 inches long, and the overall length from a proximalend of the anterior electrodes 3512A and 3512C to a distal end of theposterior electrode 3512B is about 1.8 inches. Tube 3510 is configuredto be positioned such that the vocal folds of a patient are positionedin the overlap region 3530. Thus, the configuration of the electrodes3512 above the vocal folds is different than the configuration below thevocal folds. The single posterior electrode 3512B is configured to bepositioned primarily below the vocal folds, and the two anteriorelectrodes 3512A and 3512C are configured to be positioned primarilyabove the vocal folds. It has been determined that the largest responseis provided on the anterior side at about 0.5 inches above the vocalfolds. In one embodiment, electrodes 3512A and 3512B are used for afirst EMG channel, and electrodes 3512C and 3512B are used for a secondEMG channel.

FIG. 36A shows a first side view (posterior side) of an EMG endotrachealtube 3600 with four electrodes according to one embodiment. FIG. 36Bshows a second side view (rotated 90 degrees from the view shown in FIG.36A) of the EMG endotracheal tube 3600 shown in FIG. 36A according toone embodiment. FIG. 36C is a diagram illustrating a cross-sectionalview of the endotracheal tube 3600 shown in FIGS. 36A and 36B accordingto one embodiment. As shown in FIGS. 36A-36C, endotracheal tube 3600includes tube 3610, electrodes 3612, and primary cuff 3614. Tube 3610transports gases to and from the lungs. A proximal end (left end in FIG.36A) of tube 3610 is configured to be connected to a respirating machine(not shown) for injecting air into the lungs and withdrawing air fromthe lungs. A cuff inflating conduit (not shown) is configured to beconnected to a source of compressed air (not shown) for inflating cuff3614. After endotracheal tube 3600 is inserted into the trachea of apatient, electrodes 3612 sense EMG signals, which are output to an EMGprocessing machine (e.g., NIM device 120).

Electrodes 3612 include four electrodes 3612A-3612D, which are formedaround a circumference of the tube 3610 and extend in a longitudinaldirection of the tube 3610. Electrodes 3612A and 3612B are positionedentirely on the posterior side of the tube 3610 and are also referred toherein as posterior electrodes 3612A and 3612B. Electrodes 3612C and3612D are positioned entirely on the anterior side of the tube 3610 andare also referred to as anterior electrodes 3612C and 3612D. Theanterior side of the tube 3610 is the bottom half of the tube 3610 shownin FIG. 36C, and the posterior side of the tube 3610 is the top half ofthe tube 3610 shown in FIG. 36C. Each of the electrodes 3612A-3612D iscoupled to a respective trace 3624A-3624D (trace 3624D is not visible inthe Figures). Traces 3624A-3624D are positioned in a protected (masked)region 3628 of tube 3610. Posterior electrodes 3612A and 3612B arepositioned in an exposed (unmasked) region 3626A of tube 3610. Anteriorelectrodes 3612C and 3612D are positioned in an exposed (unmasked)region 3626B of tube 3610.

In one embodiment, each of the electrodes 3612A-3612D has a length ofabout one inch, and extends laterally around a circumference of the tubefor a distance corresponding to an angle 3622 of about 60 degrees (i.e.,each of the electrodes 3612A-3612D has a width of about 16.666 percentof the total circumference of the tube). The electrodes are laterallyspaced apart around the circumference of the tube by a distancecorresponding to an angle 3620 of about 30 degrees (i.e., the lateralspacing between each of the electrodes 3612A-3612D is about 8.333percent of the total circumference of the tube). The posteriorelectrodes 3612A and 3612B are longitudinally offset or displaced fromthe anterior electrodes 3612C and 3612D. The posterior electrodes 3612Aand 3612B are positioned closer to the distal end (right side in FIGS.36A and 36B) of the tube 3610 than the anterior electrodes 3612C and3612D, and the anterior electrodes 3612C and 3612D are positioned closerto the proximal end (left side in FIGS. 36A and 36B) of the tube 3610than the posterior electrodes 3612A and 3612B.

Tube 3610 includes an overlap region 3630 where a proximal portion ofthe posterior electrodes 3612A and 3612B longitudinally overlap with adistal portion of the anterior electrodes 3612C and 3612D. Theelectrodes 3612 do not physically overlap each other since they arelaterally offset from each other. In one embodiment, the overlap region3630 is about 0.1 inches long, and the overall length from a proximalend of the anterior electrodes 3612C and 3612D to a distal end of theposterior electrodes 3612A and 3612B is about 1.9 inches. In anotherembodiment, the overlap region 3630 is about 0.2 inches long, and theoverall length from a proximal end of the anterior electrodes 3612C and3612D to a distal end of the posterior electrodes 3612A and 3612B isabout 1.8 inches. Tube 3610 is configured to be positioned such that thevocal folds of a patient are positioned in the overlap region 3630.Thus, the configuration of the electrodes 3612 above the vocal folds isdifferent than the configuration below the vocal folds. The posteriorelectrodes 3612A and 3612B are configured to be positioned primarilybelow the vocal folds, and the anterior electrodes 3612C and 3612D areconfigured to be positioned primarily above the vocal folds. In oneembodiment, electrodes 3612A and 3612C are used for a first EMG channel,and electrodes 3612B and 3612D are used for a second EMG channel. Inanother embodiment, electrodes 3612A and 3612D are used for a first EMGchannel, and electrodes 3612B and 3612C are used for a second EMGchannel.

FIG. 37A shows a first side view (posterior side) of an EMG endotrachealtube 3700 with four electrodes according to another embodiment. FIG. 37Bshows a second side view (rotated 90 degrees from the view shown in FIG.37A) of the EMG endotracheal tube 3700 shown in FIG. 37A according toone embodiment. As shown in FIGS. 37A and 36B, endotracheal tube 3700includes tube 3710, electrodes 3712, and primary cuff 3714. Tube 3710transports gases to and from the lungs. A proximal end (left end in FIG.37A) of tube 3710 is configured to be connected to a respirating machine(not shown) for injecting air into the lungs and withdrawing air fromthe lungs. A cuff inflating conduit (not shown) is configured to beconnected to a source of compressed air (not shown) for inflating cuff3714. After endotracheal tube 3700 is inserted into the trachea of apatient, electrodes 3712 sense EMG signals, which are output to an EMGprocessing machine (e.g., NIM device 120).

Electrodes 3712 include four electrodes 3712A-3712D, which are formedaround a circumference of the tube 3710 and extend in a longitudinaldirection of the tube 3710. Each of the electrodes 3712A-3712D iscoupled to a respective trace 3724A-3724D (traces 3724A and 3724D arenot visible in the Figures). Traces 3724A-3724D are positioned in aprotected (masked) region 3728 of tube 3710. Electrodes 3712C and 3712Dare positioned in an exposed (unmasked) region 3726A of tube 3710.Electrodes 3712A and 3712B are positioned in an exposed (unmasked)region 3726B of tube 3710.

In one embodiment, each of the electrodes 3712A-3712D has a length ofabout one inch. In one embodiment, each of the electrodes 3712A and3712B extends laterally around a circumference of the tube for adistance corresponding to an angle of about 140 degrees (i.e., each ofthe electrodes 3712A and 3712B has a width of about 38.888 percent ofthe total circumference of the tube). In one embodiment, each of theelectrodes 3712C and 3712D extends laterally around a circumference ofthe tube for a distance corresponding to an angle of about 110 degrees(i.e., each of the electrodes 3712C and 3712D has a width of about30.555 percent of the total circumference of the tube). Electrodes 3712Aand 3712B are laterally spaced apart from each other around thecircumference of the tube by a distance corresponding to an angle ofabout 40 degrees (i.e., the lateral spacing between the electrodes 3712Aand 3712B is about 11.111 percent of the total circumference of thetube). Electrodes 3712C and 3712D are laterally spaced apart from eachother around the circumference of the tube by a distance correspondingto an angle of about 70 degrees (i.e., the lateral spacing between theelectrodes 3712C and 3712D is about 19.444 percent of the totalcircumference of the tube). The electrodes 3712A and 3712B arelongitudinally offset or displaced from the electrodes 3712C and 3712D.The electrodes 3712C and 3712D are positioned closer to the distal end(right side in FIGS. 37A and 37B) of the tube 3710 than the electrodes3712A and 3712B, and the electrodes 3712A and 3712B are positionedcloser to the proximal end (left side in FIGS. 37A and 37B) of the tube3710 than the electrodes 3712C and 3712D.

Tube 3710 includes a separation region 3730 where a proximal end of theelectrodes 3712C and 3712D is longitudinally separated from a distal endof the electrodes 3712A and 3712B. In one embodiment, the separationregion 3730 is about 0.1 inches long, and the overall length from aproximal end of the electrodes 3712A and 3712B to a distal end of theelectrodes 3712C and 3712D is about 2.1 inches. In another embodiment,the separation region 3730 is about 0.2 inches long, and the overalllength from a proximal end of the electrodes 3712A and 3712B to a distalend of the electrodes 3712C and 3712D is about 2.2 inches. Tube 3710 isconfigured to be positioned such that the vocal folds of a patient arepositioned in the separation region 3730. Thus, the configuration of theelectrodes 3712 above the vocal folds is different than theconfiguration below the vocal folds. The electrodes 3712C and 3712D areconfigured to be positioned primarily below the vocal folds, and theelectrodes 3712A and 3712B are configured to be positioned primarilyabove the vocal folds.

FIG. 38 shows a side view of an EMG endotracheal tube 3800 with aplurality of ring electrodes according to one embodiment. As shown inFIG. 38, endotracheal tube 3800 includes tube 3810, electrodes 3812, andprimary cuff 3814. Tube 3810 transports gases to and from the lungs. Aproximal end (left end in FIG. 38) of tube 3810 is configured to beconnected to a respirating machine (not shown) for injecting air intothe lungs and withdrawing air from the lungs. A cuff inflating conduit(not shown) is configured to be connected to a source of compressed air(not shown) for inflating cuff 3814. After endotracheal tube 3800 isinserted into the trachea of a patient, electrodes 3812 sense EMGsignals, which are output to an EMG processing machine (e.g., NIM device120).

Electrodes 3812 include a plurality of ring electrodes 3812A. In oneembodiment, each of the ring electrodes 3812A completely surrounds acircumference of the tube 3810. In one embodiment, electrodes 3812include sixteen ring electrodes 3812A that are longitudinally separatedfrom each other along the length of the tube by a distance of about 0.05inches, and have an overall length in the longitudinal direction of thetube of about 1.55 inches.

FIGS. 39A-39E show EMG endotracheal tubes with tube placement markingsaccording to various embodiments. In one embodiment, the tube markingsshown in FIGS. 39A-39E are formed from a radio opaque material.

As shown in FIG. 39A, EMG endotracheal tube 3900A includes three bands3902, 3904, and 3906, and a vertical line segment 3908. The bands 3902,3904, and 3906, and the vertical line segment 3908, are positioned on anelectrode region of the tube 3900A, and facilitate proper longitudinaland rotational positioning of the electrodes of tube 3900A with respectto a patient's anatomy. Bands 3902, 3904, and 3906 are positionedadjacent to each other, with band 3904 positioned between band 3902 and3906. In one embodiment, each of the bands 3902, 3904, and 3906surrounds a circumference of the tube 3900A or a portion of thecircumference of the tube 3900A, and the bands 3902, 3904, and 3906 havean overall length along a longitudinal axis of the tube 3900A that isthe same or substantially the same as the length of the electrodes oftube 3900A. In one embodiment, bands 3902 and 3906 have substantiallythe same length, which is about twice as long as the length of band3904. Bands 3902, 3904, and 3906 are solid color bands in oneembodiment, and at least two different colors are used for the threebands. In one embodiment, bands 3902, 3904, and 3906 are each a solidcolor band with a different color than the other bands (i.e., 3different solid colors are used for the three bands). In one form ofthis embodiment, band 3902 is a green band, band 3904 is a white band,and band 3906 is a blue band. The colors are selected in one embodimentto differentiate the bands from blood and surrounding tissue. Verticalline segment 3908 extends in a longitudinal direction along tube 3900A,and has a length that is the same or substantially the same as theoverall length of the bands 3902, 3904, and 3906.

As shown in FIG. 39B, EMG endotracheal tube 3900B includes band 3910,vertical line segment 3914, and horizontal line segments 3916, 3918, and3920. The band 3910 and the line segments 3914, 3916, 3918, and 3920 arepositioned on an electrode region of the tube 3900B, and facilitateproper longitudinal and rotational positioning of the electrodes of tube3900B with respect to a patient's anatomy. In one embodiment, band 3910surrounds a circumference of the tube 3900B, and has a length along alongitudinal axis of the tube 3900B that is the same or substantiallythe same as the length of the electrodes of tube 3900B. Band 3910 is asolid color band in one embodiment. In one embodiment, band 3910 is awhite band. In another embodiment, band 3910 is a blue band. The coloris selected in one embodiment to differentiate the band from blood andsurrounding tissue.

Vertical line segment 3914 extends in a longitudinal direction alongtube 3900B, and has a length that is the same or substantially the sameas the length of the band 3910. Each of the horizontal line segments3916, 3918, and 3920 intersects the vertical line segment 3914 andextends in a lateral direction around a portion of the circumference ofthe tube 3900B. The horizontal line segments 3916, 3918, and 3920 areeach centered on the vertical line segment 3914, and are spaced apartfrom each other along a longitudinal axis of the tube 3900B. Horizontalline segment 3918 is positioned between segments 3916 and 3920.Horizontal line segments 3916 and 3920 have the same length in oneembodiment, which is less than the length of segment 3918. In oneembodiment, segment 3918 has a length that is at least about twice aslong as the length of each of the segments 3916 and 3920.

As shown in FIG. 39C, EMG endotracheal tube 3900C includes band 3922,vertical line segment 3926, horizontal line segment 3928, and diagonalline segments 3930 and 3932. The band 3922 and the line segments 3926,3928, 3930, and 3932 are positioned on an electrode region of the tube3900C, and facilitate proper longitudinal and rotational positioning ofthe electrodes of tube 3900C with respect to a patient's anatomy. In oneembodiment, band 3922 surrounds a circumference of the tube 3900C, andhas a length along a longitudinal axis of the tube 3900C that is thesame or substantially the same as the length of the electrodes of tube3900C. Band 3922 is a solid color band in one embodiment. In oneembodiment, band 3922 is a white band. In another embodiment, band 3922is a blue band. The color is selected in one embodiment to differentiatethe band from blood and surrounding tissue.

The line segments 3926, 3928, 3930, and 3932 all intersect at a commonpoint 3924. Vertical line segment 3926 extends in a longitudinaldirection along tube 3900C, and has a length that is the same orsubstantially the same as the length of the band 3922. The horizontalline segment 3928 is centered on the vertical line segment 3926 andextends in a lateral direction around a portion of the circumference ofthe tube 3900C. Diagonal line segments 3930 and 3932 extendlongitudinally and laterally along tube 3900C and intersect each otherat common point 3924 to form an x-type marking.

As shown in FIG. 39D, EMG endotracheal tube 3900D includes band 3934,triangular markings 3936 and 3940, and vertical line segment 3942, whichare positioned on an electrode region of the tube 3900D, and facilitateproper longitudinal and rotational positioning of the electrodes of tube3900D with respect to a patient's anatomy. In one embodiment, band 3934surrounds a circumference of the tube 3900D, and has a length along alongitudinal axis of the tube 3900D that is the same or substantiallythe same as the length of the electrodes of tube 3900D. Band 3934 is asolid color band in one embodiment. In one embodiment, band 3934 is awhite band.

Each of the triangular markings 3936 and 3940 according to oneembodiment has substantially the shape of an isosceles triangle. Each ofthe triangular markings 3936 and 3940 has a base segment that extendslaterally around a portion of the circumference of the tube 3900D, andtwo equal sides that extend away from the base portion and meet at anapex of the triangle. The apexes of the triangular markings 3936 and3940 share a common point 3938. Each of the triangular markings 3936 and3940 is a solid color marking in one embodiment. In one embodiment, thecolor of marking 3936 is different than the color of marking 3940. Inone form of this embodiment, marking 3936 is a green marking, andmarking 3940 is a blue marking. The colors are selected in oneembodiment to differentiate the markings from blood and surroundingtissue.

Vertical line segment 3942 extends in a longitudinal direction alongtube 3900D from the middle of the base segment of the triangular marking3936 to the middle of the base segment of the triangular marking 3936,and intersects the common point 3938. Vertical line segment 3942 has alength that is the same or substantially the same as the length of theband 3934.

As shown in FIG. 39E, EMG endotracheal tube 3900E includes band 3950,vertical line or strip 3952, and horizontal line or strip 3954, whichare positioned on an electrode region of the tube 3900E, and facilitateproper longitudinal and rotational positioning of the electrodes of tube3900E with respect to a patient's anatomy. In one embodiment, band 3950surrounds a circumference of the tube 3900E. Band 3950 is a solid colorband in one embodiment.

Vertical strip 3952 extends in a longitudinal direction along tube3900E, and has a length that is the same or substantially the same asthe length of the electrodes of tube 3900E. Vertical strip 3952 includestwo end portions 3952A and 3952C separated by a middle portion 3952B. Inone embodiment, the end portions 3952A and 3952C have a substantiallyequal length, which is about four times longer than the length of themiddle portion 3952B. Band 3950 extends from a bottom end of verticalstrip end portion 3952A to a top end of vertical strip middle portion3952B.

Horizontal strip 3954 intersects the vertical strip 3952 at the middleportion 3952B, and extends in a lateral direction around at least aportion of the circumference of the tube 3900E. In one embodiment, band3950 is a solid color band (e.g., gray), and horizontal strip 3954 is asolid color strip (e.g., white). In one embodiment, vertical stripportions 3952A and 3952C are formed from the same solid color (e.g.,blue), which is different than the solid color of vertical strip portion3952B (e.g., white). The colors are selected in one embodiment todifferentiate the bands from blood and surrounding tissue.

One embodiment is directed to an apparatus for monitoring EMG signals ofa patient's laryngeal muscles. The apparatus includes an endotrachealtube having an exterior surface and conductive ink electrodes formed onthe exterior surface. The conductive ink electrodes are configured toreceive the EMG signals from the laryngeal muscles when the endotrachealtube is placed in a trachea of the patient. At least one conductor iscoupled to the conductive ink electrodes and is configured to carry theEMG signals received by the conductive ink electrodes to a processingapparatus.

The conductive ink electrodes according to one embodiment comprise asilver filled polymer conductive ink or a carbon conductive ink. In oneembodiment, the conductive ink electrodes include at least sixconductive ink electrodes that extend longitudinally along a length ofthe tube and that are spaced apart to surround a circumference of theendotracheal tube. The apparatus according to one embodiment includes aninflatable cuff connected to the endotracheal tube, and at least oneconductive ink electrode formed on the inflatable cuff and configured tosense EMG signals from vocal folds of the patient. In one embodiment, atleast one of a light source and a magnet is positioned on theendotracheal tube near the conductive ink electrodes.

One embodiment of the apparatus includes a coupling adapter configuredto allow a proximal end of the endotracheal tube to rotate with respectto a distal end of the endotracheal tube. In one embodiment, theapparatus includes a first rib surrounding the endotracheal tube andpositioned above the conductive ink electrodes on the endotracheal tube,and a second rib surround the endotracheal tube and positioned below theconductive ink electrodes on the endotracheal tube. At least oneautomatic periodic stimulation (APS) electrode is formed on theendotracheal tube in one embodiment, and the processing apparatus isconfigured to determine a position of the endotracheal tube based onsignals generated by the at least one APS electrode. In one embodiment,at least one of a conducting hydro gel and an expandable, conductivefoam is formed on the electrodes.

The endotracheal tube comprises a braided endotracheal tube in oneembodiment. In one embodiment, the electrodes include four electrodesand the at least one conductor includes at least four pairs ofconductors, and each pair of conductors is coupled to a different pairof the four electrodes to provide at least four channels of EMG signalsfrom the four electrodes. In one form of this embodiment, the processingapparatus is configured to analyze the four channels of EMG signals andidentify a subset of the four channels to display based on the analysis.At least one wireless sensor is provided on the endotracheal tube in oneembodiment, with the at least one wireless sensor configured towirelessly transmit information to the processing apparatus. In oneembodiment, each of the electrodes is at least about 1.9 inches inlength. The electrodes form an electrode grid with at least twohorizontal electrodes and at least two vertical electrodes. In oneembodiment the apparatus includes at least one of a temperature sensingelement, fiber optic element, and video element. In one embodiment, theapparatus includes at least one of a strain measurement element, anacceleration measurement element, and a piezoelectric element.

Another embodiment is directed to a method of monitoring EMG signals ofa patient's laryngeal muscles. The method includes providing anendotracheal tube having an exterior surface and conductive inkelectrodes formed on the exterior surface. The EMG signals from thelaryngeal muscles are sensed with the conductive ink electrodes when theendotracheal tube is placed in a trachea of the patient. The EMG signalssensed by the conductive ink electrodes are output to a processingapparatus.

Another embodiment is directed to an apparatus for monitoring EMGsignals of a patient's laryngeal muscles. The apparatus includes anendotracheal tube having an exterior surface. Four electrodes are formedon the exterior surface of the endotracheal tube. The four electrodesare configured to receive the EMG signals from the laryngeal muscleswhen the endotracheal tube is placed in a trachea of the patient. Atleast four pairs of conductors are coupled to the four electrodes andconfigured to carry the EMG signals received by the electrodes to aprocessing apparatus. Each pair of the conductors is coupled to adifferent pair of the four electrodes to provide at least four channelsof EMG signals from the four electrodes.

Although embodiments set forth herein have been described in the contextof an EMG endotracheal tube, it will be understood that the techniquesare also applicable to other types of devices, such as a tube formonitoring a patient's anal sphincter or urethral sphincter.

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. An apparatus for monitoring EMG signals of apatient's laryngeal muscles, comprising: an endotracheal tube having anexterior surface and a first location configured to be positioned at thepatient's vocal folds; a first electrode formed on the exterior surfaceof the endotracheal tube substantially below the first location; and asecond electrode formed on the exterior surface of the endotracheal tubesubstantially above the first location, wherein the first and secondelectrodes are laterally and longitudinally offset from each other andconfigured to receive the EMG signals from the laryngeal muscles whenthe endotracheal tube is placed in a trachea of the patient.
 2. Theapparatus of claim 1, and further comprising: at least one conductorcoupled to the first and second electrodes and configured to carry theEMG signals received by the electrodes to a processing apparatus.
 3. Theapparatus of claim 1, wherein the first electrode is formed on aposterior side of the endotracheal tube.
 4. The apparatus of claim 1,wherein the second electrode is formed on an anterior side of theendotracheal tube.
 5. The apparatus of claim 1, wherein the firstelectrode and the second electrode each have a length of about one inch.6. The apparatus of claim 1, wherein each of the first electrode and thesecond electrode extends laterally around a circumference of the tubefor a distance corresponding to an angle of about 60 degrees to 90degrees.
 7. The apparatus of claim 1, and further comprising: a thirdelectrode formed on the exterior surface of the endotracheal tubesubstantially above the first location.
 8. The apparatus of claim 7,wherein the first electrode is formed on a posterior side of theendotracheal tube, and the second and third electrodes are formed on ananterior side of the endotracheal tube.
 9. The apparatus of claim 1, andfurther comprising: a third electrode formed on the exterior surface ofthe endotracheal tube substantially above the first location; and afourth electrode formed on the exterior surface of the endotracheal tubesubstantially below the first location.
 10. The apparatus of claim 9,wherein the first and fourth electrodes are formed on a posterior sideof the endotracheal tube, and the second and third electrodes are formedon an anterior side of the endotracheal tube.
 11. A method of monitoringEMG signals of a patient's laryngeal muscles, comprising: providing anendotracheal tube having an exterior surface with electrodes formedthereon, wherein the endotracheal tube includes a first locationconfigured to be positioned at the patient's vocal folds, wherein theelectrodes include a first electrode positioned substantially below thefirst location and a second electrode positioned substantially above thefirst location, and wherein the first and second electrodes arelaterally and longitudinally offset from each other; sensing the EMGsignals from the laryngeal muscles with the electrodes when theendotracheal tube is placed in a trachea of the patient; and outputtingthe EMG signals sensed by the conductive ink electrodes to a processingapparatus.
 12. An apparatus for monitoring EMG signals of a patient'slaryngeal muscles, comprising: an endotracheal tube having an exteriorsurface; at least one electrode formed on the exterior surface in anelectrode region of the endotracheal tube, the at least one electrodeconfigured to receive the EMG signals from the laryngeal muscles whenthe endotracheal tube is placed in a trachea of the patient; and asecond electrode formed on the exterior surface of the endotracheal tubesubstantially above the first location, wherein the first and secondelectrodes are laterally and longitudinally offset from each other andconfigured to receive the EMG signals from the laryngeal muscles whenthe endotracheal tube is placed in a trachea of the patient; and atleast one tube placement marking positioned in the electrode region andconfigured to facilitate positioning of the at least one electrodewithin a patient, wherein the at least one tube placement markingincludes at least one band that substantially surrounds a circumferenceof the endotracheal tube, and a vertical line segment that extends in alongitudinal direction along the at least one band.
 13. The apparatus ofclaim 12, wherein the vertical line segment and the at least one bandeach have a length that is substantially the same as a length of the atleast one electrode.
 14. The apparatus of claim 12, wherein the at leastone band comprises a plurality of solid color bands surrounding acircumference of the endotracheal tube.
 15. The apparatus of claim 14,wherein the plurality of solid color bands includes three differentcolored bands.
 16. The apparatus of claim 12, wherein the at least onetube placement marking further comprises a plurality of horizontal linesegments that are each centered on the vertical line segment and arespaced apart from each other in the longitudinal direction.
 17. Theapparatus of claim 12, wherein the at least one tube placement markingfurther comprises first and second diagonal line segments that intersecteach other at a common point and form an x-type marking.
 18. Theapparatus of claim 17, wherein the vertical line segment intersects thefirst and second diagonal line segments at the common point.
 19. Theapparatus of claim 12, wherein the at least one tube placement markingfurther comprises a first solid color triangular shaped marking and asecond solid color triangular shaped marking.
 20. The apparatus of claim12, wherein the vertical line segment includes two solid color endportions separated by a solid color middle portion, and wherein themiddle portion is formed of a color that is different than a color ofthe end portions.